Low-density polyester resin foams and method of preparation

ABSTRACT

Low-density polyester foams are prepared from an admixture which comprises in combination a liquid unsaturated curable polyester resin, a peroxide curing agent, an accelerator, a hydrazide blowing agent and an aliphatic amine which controls the rate of polymerization of the resin, so as to permit expansion of the resin in a selective manner to obtain a low-density polyester foam.

United States Patent [191 Jacobs et al.

[ Nov. 18, 1975 LOW-DENSITY POLYESTER RESIN FOAMS AND METHOD OFPREPARATION [75] Inventors: Richard L, Jacobs, Yorba Linda;

Donald A. Backley, Garden Grove;

James V. Simpson, Anaheim, all of Calif.; Walter Beck, Bedford, Mass.

[73] Assignee: Stepan Chemical Company,

Northfield, Ill.

[22] Filed: July 18, 1974 [21] App], No.: 489,821

[52] US. Cl 260/2.5 N; 260/2.5 B; 260/22 CB; 260/22 XA; 260/22 CA;260/23 P; 260/863; 260/864; 260/865; 260/866; 260/869 [51] Int. Cl.C08,] 9/00; C08L 67/06 [58] Field of Search 260/2.5 N, 2.5 B

[56] References Cited UNITED STATES PATENTS 3,227,665 l/1966 Fourcade etal. 260/2.5 N

3,232,893 2/1966 Salgado et al. 260/2.5 N 3,252,923 5/1966 Salgado elal. N 3,260,688 771966 Watanabe et al N 3,367,890 2/1968 McManimie N3,786,004 l/i974 Furuya et-al 260/2.5 N

FOREIGN PATENTS OR APPLICATIONS 652,770 5/1951 United Kingdom 260/2.5 N

Primary Examiner-Richard B. Turer Attorney, Agent, or Firm-Richard P.Crowley [5 7] ABSTRACT 25 Claims, No Drawings LOW-DENSITY POLYESTERRESIN FOAMS AND METHOD OF PREPARATION BACKGROUND OF THE INVENTIONPolyester foams have, in the past, been prepared by a number oftechniques; however, the methods employed and the foams produced havenot been wholly satisfactory or commercially successful. Various agentsand methods have been used in order to extend or expand unsaturatedpolyester resin (for example, see U.S. Pat. Nos. 3,470,114 and 3,673,132and French Patent 2,062,608).

Polyester foams have been prepared by mechanical frothing techniques andby the use of chemical blowing agents. The use of hydrazide, hydrazo,azo and diazobased chemical blowing agents which thennally decompose athigh temperatures to provide expanded elastomers and thermoplasticpolymers is well known (for example, see U.S. Pat. No. 3,461,087). Theuse of chemical blowing agents to date has been unsuccessful inexpanding liquid polyester resins to low-density foams. Often thedecomposition temperature of the blowing agent is either too high or toolow to obtain a proper foam product.

In some compositions, the blowing agent does not function in thepresence of the particular curing system used in polymerizing the resin.For example, hydrazide blowing agents are stable and nonreactive, orreact very slowly, with some peroxides at room temperatures of 80F, andat slightly above room temperatures even in high concentrations. Theaddition of such chemical blowing agents to liquid unsaturated polyesterresins does not cause the proper expansion of the polyester resins atroom temperature upon catalysis by the peroxide alone. Further,admixtures of such blowing agents, peroxides and polyester resins do notcause expansion of the polyester resins, except upon the application ofexternal heat. The external heat process is most difficult to control,and only a slight degree of expansion is obtained even under suchconditions. Typically, the high-density foam produced exhibits severecracking resulting from the delayed expansion of the foam resin afterpolymerization of the liquid resin.

A commercially available blowing agent known as OBSl-I-( 4,4 'oxybis(benezenesulfonyl hydrazide has been employed in peroxide catalyzedliquid unsaturated polyester resins to produce high-density polyesterfoams; however, such foams have not been satisfactory. OBSH normally hasa decomposition temperature in air 'tion of the decomposition, makingsuch technique of about 150C and in plastics of about 130 to 140C.

Commercially, OBSH is used as a blowing agent in thermoplastics, such asvinyl-chloride resins and olefinic-type resins. However, when employedin typical liquid polyester resins, a foam density of not less thanabout 50 pounds per cubic foot (pcf) is usually obtained whichrepresents only a 10 to 30% expansion. The foam so obtained is oftencharacterized by severe surface-cracking, splitting, nonuniform cells orother defects, since polymerization substantially occurs well prior tofull decomposition of the OBSH blowing agent.

The decomposition temperature of OBSI-l has been lowered by the actionof certain peroxides inparticular saturated polysulfide rubbersemploying OBSH; e.g., with a lead peroxide at room temperature (see, forexample, U.S.- Pat. Nos. 3,095,387 and 3,114,723). However, the rate ofdecomposition in such systems is very slow, with several hours at leastrequired for'complecommercially impractical.

Some of the chemical blowing agents previously referred to becomereactive with certain peroxides at low temperatures when in the presenceof other chemicals known as promoters ancl accelerators. Admixtures ofthese chemicals in a liquid unsaturated polyester resin cause expansionof the polyester to provide a polyester foam. However, the foam producedis unsatisfactory and is not of low density. The expansion in suchsystems only partially occurs before polymerization. Since expansioncontinues to occur after polymerization of the liquid resin by theresidual previously unreactive blowing agents, continued expansionresults in diminished efficiency of the blowing agent, unacceptablecracking within the polyester foam produced and foams of high density. 1

In summary, although polyester foams have been produced, these foams andthe techniques employed in preparing these foams have not provencommercially successful or wholly practical. A method of producingpolyester foams of low density, for example, less than about 40 pounds,such as, 30 pounds per cubic foot (pcf), would be'most desirable. Suchmethod and the foams produced provide a significant economic advantagein the value of the material saved by the weight reduction. In addition,the availability of acceptable lowdensity polyester foams permits manynew applications for polyester resins, such as its use as a rigid foamstructural material, and in thermal, electrical and accousticalinstallations, for buoyancy and in many other fields.

SUMMARY OF THE INVENTION I Our invention concerns low-density polyesterresin foams, liquid polyester resin foamable compositions. from whichsuch foams are prepared, and the method of preparing such compositionsand such foams.

In particular, the liquid foamable polyester resin composition fromwhich our polyester foams are prepared comprises: a liquid unsaturatedpolyester resin lective manner prior to the curing of the resin, therebyproviding for the production of a low-density polyester foam from theliquid foamable composition.

In our liquid foamable composition, each of the foregoing componentsmust be present in combination in order to provide that the rate ofpolymerization of the polyester resin and the rate of decomposition ofthe blowing agent are selectively and properly matched. In such acomposition, the liquid resin composition contains sufficient strengthin the early gel stages or phases to retain the gas generated by theblowing agent. In the later stages of such composition, the rate of curedoes not progress so rapidly, so as to provide a high-density tion ofthe blowing-agent. Our invention provides a composition for and a methodof so adjusting the rate of decomposition and the rate of cure toprovide for a 3 new and unique polyester foam characterized by a verylow density, usually less than 30 pcf; e.g.,v 20 pcf, and

good foam characteristics. Our foams have a lack of or I a substantialreduction in internal stresses and surface cracking, and exhibit uniformcellular structure. Our method permits polyester foams often having adensity as low as pcf or lower to be prepared; for example, rigid andsemirigid foams of from about 8 to 30 pcf.

Furthermore, our invention permits the preparation of two-componentliquid systems whose components are blends which are stable for periodsexceeding three months. These two-component systems are mixed in ratiosvarying from 1:1 to 50:1 by weight, depending upon the applicationproperties and final physical properties desired. These components areimmediately reactive even after standing for three months attemperatures no greater than 85F to give foams which have essentiallythe same properties as those blends immediately prepared. The blends ofthe liquid polyester resin, the blowing agents, the accelerator orpromoter and other redox compounds are stable, provided that theperoxide catalyst is retained in the second component. The peroxidecomponent is prepared in a blend of hydroxyl-bearing resins and isstable indefinitely even in the presence of certain of these compounds.

The liquid unsaturated polyester resins in our composition comprise alinear or only slightly branched polyester resin and a peroxidecross-linkable monomeric compound. The linear or slightly branchedpolyester resin is typically prepared as a condensation or reactionproduct of an unsaturated polybasic and a polyhydric comp und; forexample, the condensation product of an unsaturated dibasic acid ofalpha-beta ethylenic unsaturation and a di or trihydric compound, suchas a glycol. Often a saturated polybasic acid or anhydride, such as adibasic acid, is employed with the unsaturated acid or anhydride tomodify the reactivity of the unsaturated resin.

Examples of typical polyhydric alcohols include, but are not limited to:ethylene glycol; 1,2-propane diol; 1,3-propane diol; diethylene glycol;dipropylene glycol; triethylene glycol; tripropylene glycol; 1,2-butanediol; 1,3-butane diol; 1,4-butane diol; neopentyl glycol;2,2,5-trimethylpentane diol; cyclohexanedimethanol; dibromoneopentylglycol; dibromobutane diol; trimethylolpropane; pentaerythritol;trimethylpentane diol; dipropoxy adducts of his phenol A; and dipropoxyadducts of hydrogenated bis phenol A.

Examples of saturated polybasic acids include, but are not limited to:isophthalic acid; orthophthalic acid; terephthalic acid;tetrabromophthalic acid; tetrachlorophthalic acid; tetrahydrophthalicacid; adipic acid;

succinic acid; azelaic acid; glutaric acid; nadic acid and the variousanhydrides obtained therefrom.

Examples of unsaturated polybasic acids include, but are not limited to:maleic acid; fumaric acid; itaconic acid; citraconic acid and anhydridesobtained therefrom.

Examples of peroxide curable cross-linking monomers employed with thelinear polyesters include, but are not limited to: styrene; vinyltoluene; acrylates and methacrylates like methylmethacrylate;alphamethyl styrene; chloro styrene; and diallyl phthalate. The liquidunsaturated polyester resins also typically contain small amounts ofinhibitors in order to prevent premature reaction, such as, for example:hydroquinone; quinone and tertiary butyl catechol. These monomers, thesaturated acids, the unsaturated acids and the polyhydric compounds maybe admixed together in various proportions as is known in the art inorder to obtain resins with varying prope rties, typically in amounts ofabout 0 to 50% by weight; for example, such as 5 to 45%. Such liquidresin compositions may include. a wide variety of other additives toinclude: viscosity index improvers; rheological agents; flameretardants; thermoplastic polymers; fillers such as hollow glass orplastic microsphere beads; wood flour; silica; diatomaceous earth;pigments; dyes; stabilizers; glass fibers; release agents; extenders;catalysts; alumina surfactants; and other additives (see, for example,compounds in Unsaturated Polyester, Modern Plastics Encyclopedia, Volume50, No. 10a, 1973-1974, pp. 66-68, hereby incorporated by reference).

The components of the polyester resins may be varied as is known in theart to impart the desired properties to the cured resin. Typically,flexible resins employ greater amounts of adipates or azeleates, whilemore rigid resins use phthalates, both with a variety of differentglycols. Our invention is directed particularly to rigid and semirigidpolyester foams useful as structuraltypefoams, Such resins have aformulation, for example, of about 3 to 7 moles of glycol, 1.5 to 3.0moles of adipic acid, 0 to 1.5 moles of phthalic anhydride, and 2 to 4moles of maleic anhydride, with from 1.0 to 4 moles of styrene or vinyltoluene.

However, particular emphasis is placed on formulating the resin tocontain. high amounts of linear dibasic glycols and linear dibasicacids; e.g., over 70%, while maintaining a low amount of aromaticdihydric acids and anhydrides, unsaturated acids, and monomers in orderto impart to the resin a substantial degree of elasticity not found intypical polyester resins. Formulating for these properties becomeslimited by the desired rigidity and heat resistance propertiesof thefinished foam product. Polyester resins modified to have this elasticityand containing atypically high levels of metal; e.g., cobaltaccelerators or promoters, allow expansion to proceed in a moreunrestricted fashion than for highly cros-linked and more rigidpolymers. Foams having densities ranging from 30 to 40 pcf, butsometimes lower than 30 pcf, are obtained characterized by havingsubstantial cracking and splitting, because polymerization substantiallyoccurs prior to full decomposition of the blowing agent.

The liquid unsaturated polyester resins of our composition are employedin conjunction with a free-radical curing compound or a compound capableof forming a free radical. The crosslinked initiating compound istypically a peroxide, and would include peroxides capable of forming afree radical (R0. and ROF), particularly alkoxy-free radicals. Suchperoxides are characterized by their reaction with metal salts or metalsoaps which are a general class of agents known as accelerators orpromoters and redox agents.

Examples of peroxides include, but'are not limited to: all peroxidesknown as hydrogen peroxide; all hydroperoxides including saturatedaliphatic hydroperoxides; olefinic hydroperoxides; aralkylhydroperoxides; hydroperoxides of cycloaliphatic and heterocyclicorganic molecules; dialkyl peroxides; transanular peroxides;peroxyesters; peroxy derivatives of aldehydes and ketones; hydroxyalkylhydroperoxides; bis(hydroxyalkyl) peroxides; polyalkylidene peroxides;peroxy acetals. etc. The R radical of the peroxide must be a substituentusually characterized as alkyl, and must be saturated alkyl, olefinicalkyl, vinyl, allyl, benzyl, propenyl, isopropenyl, butenyl, etc.,saturated or partially unsaturated aliphatic or cycloaliphatic. R can bethe same as R or it can be a hydrogen, aryl, acyl, or aroyl substituent.Examples include: methyl hydroperoxide; ethyl hydroperoxide; t-butylhydroperoxide; dimeric benzaldehyde peroxide; dimeric benzophenoneperoxide; dimeric acetone peroxide; methylethyl ketone hydroperoxide,etc.

The preferred peroxides are hydrogen peroxide or alkoxy peroxides whichactuate at low temperatures less than 30C; e.g., to C, with an aqueoussolution of hydrogen peroxide and methylethyl ketone peroxide being themost effective peroxides. Other peroxides, such as hydroperoxides suchas cumene hydroperoxide, although useful, are less effective, whileperesters, such as tertiarybutylperbenzoate and tertiarybutylperoctoate,are less effective. Peracids, such as benzoylperoxide, are slightly lesseffective, while azobisisobutyronitrile, a free-radical generator uponthermolysis, is not effective.

The peroxide cross-linking catalyst is required in all of the liquidsaturated polyester resins in order to promote the cure of the resins.The peroxide compounds may be used alone or in combination. The amountof the peroxide used will, of course, vary, depending upon the nature ofthe peroxide, the processing temperatures employed, the degree of curingdesired, the ingredients of the liquid polyester resin and the like, allwell known by people in the art, but normally ranges from about 0.1 to2.5 parts per hundred parts of resin (phr), such as, for example, fromabout 0.5 to 2.0 parts.

The promoters or activators employed include a wide range oforgano-metallics and particularly metal salts and soaps which have abeneficial effect in activating or promoting the reaction, and which areknown and used in the trade as accelerators or promoters. Suchactivators are composed of metal salts and metal soaps typically intheir reduced polyvalent states. These compounds are characterized bytheir preferential reaction with peroxide, and their partial reactionwith the free radicals generated from the initial reaction with theperoxide. Typical activators include all metal soaps and salts andcomplexes therefrom generated by their reaction in polyester resinsystems. Such activators would include salts, soaps and complexes ofcobaltous, ferrous, vanadous, cadmium, manganous, cuprous, nickelous,stannous, plumbous, zirconium, chromous ions, etc. The anions of suchactivators may vary and are often selected to impart solubility to theactivators in the polyester system. Typical anions are carboxylates suchas C C, carboxylates, and include short-chain acids, fatty acids andnaphthenates. Such anions include acetate, propionate, butyrate,2-ethylhexoate, hexoate, octoate, laurate, oleate, linoleate, palmitate,stearate, acetoacetonates, and naphthenates. The preferred activatorsare the cobalt compounds such as cobalt octoate, cobalt acetoacetonatesand cobalt naphthenates. The activators may be used alone or incombination with other activators or metal salts. The activators may beemployed in amounts of from about 0.001 to 0.2 phr, but more typically,are used from about 0.01 to 0.1 phr.

The chemical blowing agents employed in our compositions includehydrazide-derived and hydrazine-type blowing agents which are capable ofproviding on decomposition a gas, typically nitrogen, alone or incombination with other gases, to provide for the expansion of thepolyester resin matrix. The chemical blowing agents useful in ourcompositions must be those blowing agents which are capable of beingeasily reacted with an ion or radical (RO, R0 or R0.) to liberate anactive moiety which will further decompose to liberate the gas.

The hydrazides and particularly the sulfonyl hydrazides are thepreferred class of blowing agents to be used in our compositions.Examples of blowing agents include, but are not limited to: hydrazine,adipodihydrazide; hydroxyethylhydrazine; phenylsulfonhydrazide;4,4-oxybis(benzenesulfonhydrazide); hydrazine sulfate;hydrazinemonochloride; hydrazinedichloride; hydrazine bisulfate; benzene-1,3-disulfonylhydrazide; toluene-( 4)-sulfonylhydrazide;diphenylsulfon-3 ,3 disulfonylhydrazide, and similar hydrazide andhydrazine salts and derivatives. Preferred specific compounds, due totheir commercial availability and action in our compositions, include:oxybis( benzenesulfonylhydrazide) and toluene sulfonylhydrazide. Theblowing agents are typically employed in varying amounts; however, theymay be employed in amounts ranging from about 0.1 to 15 phr, such as,for example, 0.3 to 10 phr. The blowing agents may be used alone or incombination.

Redox compounds are employed in our compositions to expand foams todensities substantially below 30 pcf while giving finished product foamswhich have essentially fine uniform cellular structure and arecharacterized by being free from voids, splits, cracks and otherdefects. The addition of these redox compounds to polyester systemscontaining the above-mentioned components in combination permitspolyester foams to be prepared having densities as low as 10 pcf orlower. Our redox amines may be used in amounts of from about 0.01 to 10phr.

Although not wishing to be bound by any particular theory or hypothesis,we believe that these low-density foams characterized by uniformcellularity are produced because the redox compounds specifically causeexpansion to precede selectively polymerization and, specifically,gelation. Gelation is not retarded or inhibited in a fashion typical ofsystems containing inhibitors. Some redox agents increase the rate ofgelation, but still cause expansion to precede polymerization. Otherredox agents do cause the gelation period to become extended. However,these redox compounds are differentiated from typical inhibitors, suchas catechols, hydroquinone and quinones in that they impartsubstantially greater expansion times while still allowingpolymerization to proceed rapidly.

We have found that particular classes of amine compounds are suitablefor retarding polymerization so that expansion is allowed substantiallyto precede polymerization, and, in particular, that aliphatic amines,such as primary 1), secondary (2) and tertiary (3) including alicyclicamines and their substituent compounds, are generally effective for thispurpose.

Typical aliphatic amines include and comprise those compounds containingone, two or three alkyl, alkenyl or alkynyl radicals, and such radicalsmay include and comprise aryl substituents, such as phenyl, halophenyl,alkylphenyl, halides such as chlorine, hydroxyl or other substituentgroups. These radicals, alone or in combination, bond to one or moreamino nitrogen atoms, usually by methylene or alkylene bridges, andtherefore, do not include the general class of amines known as aromaticamines, hydroxyl amines or haloamines.

Useful 1, 2 and 3 aliphatic amines include. but are not limited to:aqueous ammonia; alicyclic amines such as cyclohexylamines likecyclohexyl amine, morpholine, piperidine and piperazine and their alkyl,hydroxyalkyl and aminoalkyl substituents; e.g., N,N-dimethyl piperazine,N-methyl piperazine, N-methyl morpholine, N-ethyl morpholine, N-propylmorpholine, N-(2- hydroxyethyl) piperidine, etc.; alkene amines likemonoallyl amine, diallyl amine, N-methyl-N-allyl amine, etc.'; 1, 2, and3 alkyl amines like methyl amine, ethyl amine, n-propyl amine, isopropylamine, butyl amine, amyl amine, hexyl amine, dimethyl amine, diethylamine, dipropyl amine, diisopropyl amine, dibutyl amine, diamyl amine,di-2-ethylhexyl amine, di-n-octyl amine, N-methyl-N-butyl amine,N-ethyl-N-butyl amine, trimethyl amine, triethyl amine, etc.; alkanolamines like monoethanol amine, diethanol amine, triethanol amine,N-methylethanol amine, N,N-dimethylethanol amine, N,N-diethylethanolamine, N,N- diisopropylethanol amine, N-methyldiethanol amine,monoisopropanol amine, diisopropanol amine, and polyglycol amine likediethanolisopropanol amine, etc..

Useful amines include alkylene diamines and their substituent compoundswhich have comprised alkylene bridges such as n-propylene diamine,n-butylene diamine, tetramethyldiaminopropane, tetramethyldiaminobutane,N,N-dimethylamine-3-propyl amine, N,N-diethylamine-3-propyl amine,N,N-dimethylamine-4-butyl amine, N,N-dimethyl-N-ethyldiaminobutane,etc.; and poly-alkylene polyamines and their substituent compoundscomprising alkylene bridges containing from three to six methylenegroups such as di-npropylene triamine, tri-n-butylene tetramine, etc.;and other such amines which do not complex with the organo-metallicpromoter used; e.g., cobalt, to impede its function of promoting thereaction of the peroxide with the blowing agent.

We have discovered that ethylene diamines and polyethylene diamines suchas ethylene diamine, diethylene triamine and triethylene tetramine(i.e., where the amino groups are separated by an ethylenic radical) arenot effective amines in our composition. However, a specific group oftertiary (3), bridged ethylene diamines, such as triethylene diamine andits substituent compounds, are included in the class of effective aminesand are characteristically different from the other ethylene diamines bythe nature of their bridged structures imparting rigidity whichprecludes their characteristic ability to chelate with organo-metalliccompounds.

We have established that quaternary amines, such as aliphatic quaternaryammonium salts such as the hydroxide and halide salts of monoanddi-long-chain fatty acid radicals and mono and dialkyl radicals, whileproviding foams of low density, such foams are characterized by physicaldefects, such as splitting and cracking which precludes their acceptanceas commercial foam products. Thus, such quaternary salt compounds arenot within the definition of useful amines.

Tertiary (3) aromatic amines have often been used as promoters toenhance the rate of polymerization in polyester resin compositions;e.g., alkyl aniline compounds such as dimethyl aniline, diethyl aniline,and phenylalkylalkanol amines like phenylethyland phenylmethylethanolamines, and substituent compounds of p-toluidine (amino toluene).However, such compounds are not effective or useful in our compositions,since they provide little or no reduction in density, and

in some cases, increase density when employed in the foamable polyestercomposition of our invention. Thus, aromatic amines in general are notsatisfactory, providing difficulty by promoting rapid gelation and lateexpansion and other unacceptable results in use. The alkyl aminessuggested for use, however, may include other substituent radicals, suchas aryl radicals; e.g., phenyl or substituted radicals such asalkyl-substituted phenyl radicals with mono, di and trialkyl phenolssuch as methyl, ethyl, propyl and alkyl groups effective for use in ourcomposition, since the phenol groups are substituent groups separatedfrom the amino radicals by alkylene bridges.

The quaternary ammonium salts, while providing low-density foams, werecharacterized by foam structures which exhibited splitting and cracking.The aromatic amines had little or no effect on foam density or caused anincrease in density over the foam density of the control formulation.The cyclohexylamine and dibutylamines provided the best low-density foamstructures.

Although not wishing to be bound by any particular theory or hypothesisconcerning the present. invention, we believe that the redox compoundsprevent or retard polymerization in the peroxide-cured resin system byconverting the alkoxy-free radicals to an alcohol which delays thepolymerization reaction until the blowing agent is depleted, at whichtime, a typical polyesterfree radical curing occurs.

Our redox agents may be used alone or in combination with small amounts;e.g., 0.01 to 5.0 phr, of halogen-containing compounds such as chlorine,bromine and iodine, their corresponding halogen acids, such as hydrogenchloride, hydrogen bromide and hydrogen iodide, and halogen salts suchas metal salts, such as multivalent salts like ferric salts; e.g.,chloride; or alkali metal salts like potassium or sodium, as set forthin our copending applications hereby incorporated by reference and filedof even date with this application.

Typically, the composition after preparation is injected into a mold forthe preparation of a foamed molded product. If desired, the composition,prior to use or injection, may be aerated by the mechanical whipping inof air or another inert gas. The optimum temperatures for thecomposition are 65 to F, while the part can be cured at room temperatureor cured at elevated temperatures. Typical elevated cure schedulesinclude 1 hour at 200F and 1 hour at 300F. The gel times of ourcompositions range from as low as one second, but typically 0.1 to 5minutes.

Our invention will be described for the purposes of illustration onlywith the use of semirigid and rigid polyester resin compositions toprepare low-density rigid foams.

SPECIFIC EMBODIMENTS Example 1 Low-density foam resins were prepared toshow that various amines produced foams having densities substantiallyless than the density of the Control Formula not containing theseadditives.

A base resin was prepared from a blend of two liquid unsaturatedpolyester resins, herein referred to as Resin A and Resin B.

RESIN A Formula Components Weight. grams Step 1 Ethylene glycol 464.4

Propylene glycol 5708 Phthalic anhydride 1315.6

Maleic anhydride 529.2

Triphenyl phosphitc 2.8 Step 11 Styrene l 121.2

Hydroquinone 0.6

Copper (6%) naphthenate 0.12

Total charge 4004 7" Theoretical water loss (256.4)

Method of Preparation RESIN B Formula Components Weight, grams Step IAdipic acid 3736. Dipropylene glycol 10810. Theoretical water loss(760.) Step II Malcic anhydride 5020.

Phosphoric acid (85%) 10.0 Theoretical water loss (total) (1564.) StepIII Vinyl toluene 3570.

Hydroquinone 09 Copper (6%) naphthenate 0.54 Total resin 20823.44

Method of Preparation The Step I ingredients were weighed into a 22liter flask fitted with a packed column, nitrogen feed, stirrer andthermometer. A side arm connector was attached to the packed column anda condenser was attached to the side arm connector. The mixture washeated gradually to 210C to remove water until an acid number ofPreparation of the Control Formula Resin A, Resin B, cobalt (12%)octoate and OBSH were blended in. the following proportions and hereinreferred to as the Control Formula:

Control Formula Weight. grams Resin A 37.5 Resin B 12.5 Base Resin 50.0Cobalt 12%) octoate 1.0 OBSH 2.0

Total 53.0

Preparation of the Foam 53.0 grams of the Control Formula were weighedinto an 8 02. paper cup and brought to a temperature of 77i1F. 2.5 gramsof Lupersol DDM* catalyst were added to the Control Formula andhigh-shear mixed for 10 seconds using a 2-inch diameter propeller bladedriven by a /8 hp. compressed-air motor rotating at approximately 3600rpm. The bottom and sides of the cup were then scraped with a spatula toinsure complete mixing, time permitting. The mixture was allowed toexpand and gel in the cup and the gel time was recorded. After exotherm,the sample was post-cured for 1 hour at 300F, and the final density andfinal hardness were determined. (The density was obtained by the waterdisplacement method after the sample had cooled to room temperature).*Lupersol DDM is a trademark of Pennwalt Corporation for 6071 (byweight) methylethylketone peroxide.

This procedure was repeated to test the effect of adding various aminesto the Control Formula. This was accomplished by blending the statedamount of additive (Table I) into 53.0 grams of Control Formula prior tocatalysis. These samples were mixed and tests were conducted in the samemanner as for the Control Formula. The gel time, final densities andfinal hardnesses are shown in Table I.

TABLE I No. Amine Amine Added Gel Den- Additives Type Amount, Time.sity,

Grams Minutes Pcf 1 Control Formula 0.7 31.1 2 Cyclohexylaminc 1aliphatic 1.0 0.4 25.3 3 2-amino.2-methyl,

l-propanol 1 aliphatic 1.0 2.0 14.8 4 Monoethanolamine 1 aliphatic 1.09.0 20.2 1

5 Dibutylamine 2 aliphatic 1.0 0.15 14.8 6 1,4-cyclohexanebis-(methylaminc) 2 aliphatic 1.0 1.7 21.1 7 Morpholine 2 aliphatic 1.0 0.521.2 8 Z-methylpiperidinc 2 aliphatic 1.0 0.3 20.4 92,6-dimethy1piperidine 2 aliphatic 1.0 0.3 20.5 10 triethylaminc 3aliphatic 1.0 0.2 18.5 l l tricthanolamine 3 aliphatic 1.0 5.0 18.4 12diethylethanolamine 3 aliphatic 1.0 0.2 21.4 l3 N.N-dimcthy1ethanolamine3 aliphatic 1.0 0.7 16.8 .14 Tetramethylbutanc- I diamine 3 aliphatic1.0 0.25 19.6 15 1.2.4-trimcthy1piperazinc 3 aliphatic- 1.0 0.3 21.9 16N -methylmorpholinc 3 aliphatic 1.0 0.2 19.0

TABLE l-continued No. Amine Amine Added Gel Den- Additives Type Amount.Time. sity.

' Grams Minutes Pcf 17 Mixture of 80% triethylene diamine and dimethylethanolaminc 3 aliphatic 1.0 0.8 19.5 18 Dimclhyl amino methyl phenol 3aliphatic 1.0 1.2 21.0 19 Tris(dimethyl amino quaternary methyl) phcnolsalt 1.0 2.0 19.8 20 Aliquat 4" quaternary salt 1.0 0.2 20.1 21 Aliquat221*. quaternary salt 1.0 0.2 24.3 22 Anthranilic acid 1 aromatic 1.00.4 29.0 23 NN -diethylaniline 3 aromatic 1.0 0.1 29.0 24 Aniline 1aromatic 1.0 0.1 33.0 25 N-ethyLN-hydroxyethylmtoluidine 3 aromatic 1.00.1 32.6

26 Phenylethylcthanolaminc' 3 aromatic 1.0 0.1 36.7 27Phenylmethylcthanolamine 3 aromatic 1.0 0.1 43.5 28 Dimethylaniline 7 3aromatic 1.0 0.1 46.4 29 Pyridine 3 aromatic 1.0 0.5 35.4 30Methylisonicotinate 3 aromatic 1.0 0.4 38.0

salts.

Aliquat is a trademark of General Mills. lric. for aliphatic quaternaryammonium "l'rimcthyl lauryl ammonium chloride (5071) 'Dimethyl dicocoammonium chloride (75%) c. a cobalt accelerator present in an amountsufficient to promotethe cure of the polyester resin; d. a peroxidecatalyst activated at a temperature below about 100F, which catalyst ispresent in an amount to provide free radicals on decompositionsufficient to cross-link the polyester resin; and

a redox amine compound selected from the group consisting of alkylamines, alkanol amines, ammonia, alicyclic amines, alkene amines, analkyl-substituted amino alkyl phenol, an alkyl-substituted heterocyclicamine and poly C -C alkylene polyamine, which amine compounds arepresent in an amount of from about 0.01 to 10 phr to permit, during thepolyester resin reaction exotherm, the substantial decomposition of thefoaming agent to precede selectively the exothermic gelation and curingof the polyester resin composition.

2. The composition of claim 1 wherein the polyester resin is thecondensation product of adipic acid, dipropylene glycol and maleicanhydride, and the unsaturated monomer is selected from the groupconsisting of styrene and vinyl toluene.

3. The composition of claim 1 wherein the sulfonyl hydrazide moiety isselected from the group of compounds consisting ofoxybis(benzenesulfonyl hydrazide) and toluene sulfonyl hydrazide.

4. The composition of claim 1 wherein the accelerator is an oil-solublecobalt soap.

5. The composition of claim 1 wherein the accelerator is present in anamount of from about 0.001 to 0.2 phr.

6. The composition of claim 1 wherein the peroxide catalyst providesalkoxy-free radicals on decomposition.

7. The composition of claim 1 wherein the peroxide catalyst is presentin an amount of from about 0.1 to

2.5 phr.

8. The composition of claim 1 wherein the peroxide catalyst is selectedfrom the group consisting of methylethyl ketone peroxide'and aqueoushydrogen peroxide.

9. The composition of claim 1 wherein the composition contains as afiller material hollow glass microbeads.

10. The composition of claim 1 wherein the amine compound is acyclohexyl amine; 2-amino, 2-methyl, l-propanol; a monoethanol amine; adibutyl amine; l,4-cyclohexanebis(methyl amine); morpholine; 2-methylpiperidine; 2,6-dimethylpiperidine; triethyl amine; triethanolamine; diethylethanol amine; N,N- dimethylethanol amine;tetramethylbutanediamine; 1,2,4-trimethylpiperazine; N-methylmorpholine;a mixture of triethylene diamine and dimethyl ethanol amine; anddimethyl amino methyl phenol.

11. The composition of claim 1 which includes from about 0.01 to 5.0 phrof a halogen-containing redox compound.

12. A method of preparing low-density polyester foams, which methodcomprises:

a. admixing a liquid polyester resin composition which comprises i. aliquid unsaturated polyester resin in solution with an ethylenicallyunsaturated monomer subject to cross-linking by catalysis with aperoxide catalyst by its own reaction exotherm on addition of theperoxide catalyst,

ii. a sulfonyl hydrazide moiety present in an amount of from about 0.1to 15 phr as a foaming agent,

iii. a cobalt accelerator present in an amount sufficient to promote thecure of the polyester resin,

iv. a peroxide catalyst activated at a temperature below about 100F,which catalyst is present in an amount to provide free radicals ondecomposition sufficient to cross-link the polyester resin, and

v. a redox amine compound selected from the group consisting of alkylamines, alkanol amines, ammonia, alicyclic amines, alkene amines, analkyl-substituted amino alkyl phenol, an alkyl-substituted heterocyclicamine and poly C -C alkylene polyamine, which amine compounds arepresent in an amount of from about 0.01 to phr to permit, during thepolyester resin reaction exotherm, the substantial decomposition of thefoaming agent to precede selectively the exothermic gelation and curingof the polyester resin composition; and

b. expanding, by the reaction exotherm of the polyester resincomposition, the polyester resin composition after admixing of thepolyester resin composition components by decomposing all orsubstantially all of the foaming agent, such decomposition and expansionoccurring prior to the gelation of the polyester resin, therebyproviding a low-density polyester resin foam product.

13. The method of claim 12 which includes injecting the polyester resincomposition prior to gelation and curing into a mold to provide a moldedsemirigid or rigid foam product.

14. The method of claim 12 which includes aerating the polyester mixtureby high-shear mixing of the polyester resin composition prior toexpansion of the resin.

15. The method of claim 12 wherein the expanding of the polyester resinis carried out prior to gelation at a temperature of from about 65 to90F.

16. The method of claim 12 which includes expanding the polyester foamto provide a cured foam product having a density of from about 5 to 40pounds per cubic foot.

17. The method of claim 12 wherein the polyester resin is thecondensation product of adipic acid, dipropylene glycol and maleicanhydride, and the unsaturated monomer is selected from the groupconsisting of styrene and vinyl toluene.

18. The method of claim 12 wherein the sulfonyl hydrazide moiety isselected from the group of compounds consisting of oxybis(benzenesulfonyl hydrazide) and toluene solfonyl hydrazide.

19. The method of claim 12 wherein the accelerator is an oil-solublecobalt soap.

20. The method of claim 12 wherein the accelerator is present in anamount of from about 0.001 to 0.2 phr.

21. The method of claim 12 wherein the peroxide catalyst providesalkoxy-free radicals on decomposition.

22. The method of claim 12 wherein the peroxide catalyst is present inan amount of from about 0.1 to 2.5 phr.

23. The method of claim 12 wherein the peroxide catalyst is selectedfrom the group consisting of methylethyl ketone peroxide and aqueoushydrogen peroxide.

24. The method of claim 12 wherein the composition contains as a fillermaterial hollow glass microbeads.

25. The method of claim 12 wherein the amine compound is a cyclohexylamine; 2-amino, Z-methyl, lpropanol; a monoethanol amine; a dibutylamine; 1,4- cyclohexanebis(methyl amine); morpholine;2-methylpiperidine; 2,6-dimethylpiperidine; triethyl amine; triethanolamine; diethylethanol amine; N,N-dimethylethanol amine;tetramethylbutanediamine; 1,2,4-trimethylpiperazine; N-methylmorpholine;a mixture of triethylene diamine and dimethyl ethanol amine; anddimethyl amino methyl phenol.

1. AN EXPANDABLE LIQUID UNSATURATED POLYESTER RESIN COMPOSITION ADAPTEDTO EXPAND AND CURE, BY ITS REACTION EXOTHERM, INTO A LOW-DENSITYPOLYESTER RESIN FOAM PRODUCT, HICH COMPOSITION COMPRISES: A. A LIQUIDUNSATURATED POLYETER RESIN IN SOLUTION WITH AN ETHYLENICALLY UNSATURATEDMONOMER SUBJECT TO CROSS-LINKING BY CATALYSIS WITH A PEROXIDE CATALYSTBY ITS OWN REACTION EXOTHERM ON ADDITION OF THE PEROXIDE CATALYST, B. ASULFONYL HYDRAZIDE MOIETY PERSENT IN AN AMOUNT OF FROM ABOUT 0.1 TO 15PHR AS A FOAMING AGENT; C. A COBALT ACCELERATOR PERSENT IN AN AMOUNTSUFFICIENT TO PROMOTE THE CURE OF THE POLYESTER RESIN, D. A PEROXIDECATALYST ACTIVATED AT A TEMPERATURE BELOW ABOUT 100*F, WHICH CATALYST ISPERSENT IN AN AMOUNT TO PROVIDE FREE RADICALS ON DECOMPOSITIONSUFFICIENT TO CROSS-LINK THE POLYESTER RESIN, AND E. A REDOX AMINECOMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKYL AMINE, ALKANOLAMINES, AMMONIA, ALICYCLIC AMINES, ALKENE AMINES, AN ALKYL-SUBSTITUTEDAMINO ALKYL PHENOL, AN ALKYL-SUBSTITUTED HETEROCYCLIC AMINE AND POLYC2-C4 ALKYLENE POLYAMINE, WHICH AMINE COMPOUNDS ARE PRESENT IN AN AMOUNTOF FROM ABOUT 0.01 TO 10 PHR TO PERMIT, DURING THE POLYESTER RESINREACTION EXOOOTHERM, THE SUBSTANTIAL DECOMPOSITION OF THE FOAMING AGENTTO PRECEDE SELECTIVELY THE EXOTHERMIC GELATION AND CURING OF THEPOLYESTER RESIN COMPOSITION.
 2. The composition of claim 1 wherein thepolyester resin is the condensation product of adipic acid, dipropyleneglycol and maleic anhydride, and the unsaturated monomer is selectedfrom the group consisting of styrene and vinyl toluene.
 3. Thecomposition of claim 1 wherein the sulfonyl hydrazide moiety is selectedfrom the group of compounds consisting of oxybis(benzenesulfonylhydrazide) and toluene sulfonyl hydrazide.
 4. The composition of claim 1wherein the accelerator is an oil-soluble cobalt soap.
 5. Thecomposition of claim 1 wherein the accelerator is present in an amountof from about 0.001 to 0.2 phr.
 6. The composition of claim 1 whereinthe peroxide catalyst provides alkoxy-free radicals on decomposition. 7.The composition of claim 1 wherein the peroxide catalyst is present inan amount of from about 0.1 to 2.5 phr.
 8. The composition of claim 1wherein the peroxide catalyst is selected from the group consisting ofmethylethyl ketone peroxide and aqueous hydrogen peroxide.
 9. Thecomposition of claim 1 wherein the composition contains as a fillermaterial hollow glass microbeads.
 10. The composition of claim 1 whereinthe amine compound is a cyclohexyl amine; 2-amino, 2-methyl, 1-propanol;a monoethanol amine; a dibutyl amine; 1,4-cyclohexanebis(methyl amine);morpholine; 2-methylpiperidine; 2,6-dimethylpiperidine; triethyl amine;triethanol amine; diethylethanol amine; N,N-dimethylethanol amine;tetramethylbutanediamine; 1,2,4-trimethylpiperazine; N-methylmorpholine;a mixture of triethylene diamine and dimethyl ethanol amine; anddimethyl amino methyl phenol.
 11. The composition of claim 1 whichincludes from about 0.01 to 5.0 phr of a halogen-containing redoxcompound.
 12. A method of preparing low-density polyester foams, whichmethod comprises: a. admixing a liquid polyester resin composition whichcomprises i. a liquid unsaturated polyester resin in solution with anethylenically unsaturated monomer subject to cross-linking by catalysiswith a peroxide catalyst by its own reaction exotherm on addition of theperoxide catalyst, ii. a sulfonyl hydrazide moiety present in an amountof from about 0.1 to 15 phr as a foaming agenT, iii. a cobaltaccelerator present in an amount sufficient to promote the cure of thepolyester resin, iv. a peroxide catalyst activated at a temperaturebelow about 100*F, which catalyst is present in an amount to providefree radicals on decomposition sufficient to cross-link the polyesterresin, and v. a redox amine compound selected from the group consistingof alkyl amines, alkanol amines, ammonia, alicyclic amines, alkeneamines, an alkyl-substituted amino alkyl phenol, an alkyl-substitutedheterocyclic amine and poly C2-C4 alkylene polyamine, which aminecompounds are present in an amount of from about 0.01 to 10 phr topermit, during the polyester resin reaction exotherm, the substantialdecomposition of the foaming agent to precede selectively the exothermicgelation and curing of the polyester resin composition; and b.expanding, by the reaction exotherm of the polyester resin composition,the polyester resin composition after admixing of the polyester resincomposition components by decomposing all or substantially all of thefoaming agent, such decomposition and expansion occurring prior to thegelation of the polyester resin, thereby providing a low-densitypolyester resin foam product.
 13. The method of claim 12 which includesinjecting the polyester resin composition prior to gelation and curinginto a mold to provide a molded semirigid or rigid foam product.
 14. Themethod of claim 12 which includes aerating the polyester mixture byhigh-shear mixing of the polyester resin composition prior to expansionof the resin.
 15. The method of claim 12 wherein the expanding of thepolyester resin is carried out prior to gelation at a temperature offrom about 65* to 90*F.
 16. The method of claim 12 which includesexpanding the polyester foam to provide a cured foam product having adensity of from about 5 to 40 pounds per cubic foot.
 17. The method ofclaim 12 wherein the polyester resin is the condensation product ofadipic acid, dipropylene glycol and maleic anhydride, and theunsaturated monomer is selected from the group consisting of styrene andvinyl toluene.
 18. The method of claim 12 wherein the sulfonyl hydrazidemoiety is selected from the group of compounds consisting ofoxybis(benzenesulfonyl hydrazide) and toluene solfonyl hydrazide. 19.The method of claim 12 wherein the accelerator is an oil-soluble cobaltsoap.
 20. The method of claim 12 wherein the accelerator is present inan amount of from about 0.001 to 0.2 phr.
 21. The method of claim 12wherein the peroxide catalyst provides alkoxy-free radicals ondecomposition.
 22. The method of claim 12 wherein the peroxide catalystis present in an amount of from about 0.1 to 2.5 phr.
 23. The method ofclaim 12 wherein the peroxide catalyst is selected from the groupconsisting of methylethyl ketone peroxide and aqueous hydrogen peroxide.24. The method of claim 12 wherein the composition contains as a fillermaterial hollow glass microbeads.
 25. The method of claim 12 wherein theamine compound is a cyclohexyl amine; 2-amino, 2-methyl, 1-propanol; amonoethanol amine; a dibutyl amine; 1,4-cyclohexanebis(methyl amine);morpholine; 2-methylpiperidine; 2,6-dimethylpiperidine; triethyl amine;triethanol amine; diethylethanol amine; N,N-dimethylethanol amine;tetramethylbutanediamine; 1,2,4-trimethylpiperazine; N-methylmorpholine;a mixture of triethylene diamine and dimethyl ethanol amine; anddimethyl amino methyl phenol.